This is a great post from Mashable and Sharlyn Lauby about how Twitter can help you communicate with your customers better along with educating them about your history, awards, and future plans.
Sharlyn also talks about the importance of asking questions via Twitter in order to get immediate (and usually useful) customer feedback.
I found that companies that have an honest and open company culture are often the best Twitterers. Dell has a social media department and several other companies allow their employees to regularly update their personal (and the company’s) Twitter accounts on the clock during the work day so customers stay continuously updates with what the company and its employees are doing.
You can view the article here.